Combined air filter and needle valve



mm m M a a? a W k A. w J W March 1952 c. L. SNYDER ET AL COMBINED AIRFILTER AND NEEDLE VALVE Patented Mar. 25, 1952 COMBINED AIR FILTER ANDNEEDLE VALVE Cyrus L. Snyder, Hawthorne, and John W. Schroeder, LosAngeles, Calif., assignors, by direct and mesne assignments, to LucileM. Hursh, San Marino, Calif.

Application August 31, 1948, Serial No. 47,086

Cur invention relates generally to carburetors for internal combustionengines and more particularly to the idling fuel supply systemstherefor.

In the conventional carburetor, it is the usual practice to provide abypass conduit to conduct liquid fuel past the throttle valve so thatwhen the latter is nearly closed, e. g., in idling condition, a smallamount of fuel will still be supplied to the engine for idling purposes.When the throttle is nearly closed, as stated, a partial vacuum iscreated in the intake manifold and serves to draw the liquid fuelthrough the aforesaid bypass. It is further practice to provide suchidling fuel conduit with a needle valve so that iohte amount of idlingfuel delivered may be regua ed.

One of the disadvantages of the system just described is that the fuel,usually gasoline, is delivered in an unatomized liquid condition intothe intake manifold, thus making for very inefficient operation of theengine during idling conditions. This undesirable condition of the fuelduring idling period is due to the fact that the air is supplied throughthe intake manifold past the nearly closed throttle valve and when itreaches the idling fuel inlet, is moving at a relatively low velocity.Thus, there is no atomizing effect of the air on the fuel with theresult that the latter is delivered in relatively large droplets, ratherthan in atomized form, as is the case with fuel delivered by the highspeed jets into a relatively high velocity air stream.

Some efforts have been made in the past to overcome the above diflicultyby providing an auxiliary airinlet port immediately adjacent the needlevalve controlling the idling fuel. In some cases, this has been done bydrilling an axial hole clear through the needle valve to admit air atthe tip of the needle valve where it is mixed with the liquid fuel. Thedisadvantage of this latter arrangement is that while the needle valveserves to regulate the flow of liquid fuel, the axial airbleed holethrough the center of the needle valve is unaffected by adjustmentthereof and thus it is impossible .to properly regulate the mixture ofair and fuel.

Still other efforts have been made to provide air-bleed passages throughthe needle valve by drilling an axial hole partially through the needlevalve and then connecting the same with a radial hole through the sideof the valve.

A single radial hole of the type just described is not satisfactory,however, since rotation of the valve for the purpose of adjusting theneedle relative to its seat rotates the air-bleed hole to 5 Claims. (Cl.183-44) various positions with respect to the adjacent fuel passage.Thus, the radial hole through which air is admitted to mix with the fuelmay or may not be in an optimum position when the needle valve isadjusted to its optimum position relative to the seat.

A still further disadvantage encountered with previous air-bleed systemsof the class described is that the air-bleed passage, being necessarilysmall, tends to become plugged with the everpresent grease and dirtvifhich accumulates on automotive engines. Still further, particles ofdirt or other foreign matter may enter through the air-bleed hole, butbecome lodged in the fuel passage, whereby to completely clog the idlingfuel supply and prevent the engine from idling at all.-

Bearing in mind the foregoing disadvantages of previous idling fuelsupply systems, it is a major object of the present invention to providemeans for admitting a supply of air into the idling fuel system wherebyto eifect efiicient motor operation during idling periods.

It is another object-of our invention to provide an air passage of theclass described which is incorporated in the needle valve'itself inorder that such valve may be replaced in existing engines to increasetheefliciency thereof.

It is still another object of my invention to provide a needle valvehaving an air passage therein which is adapted for eflicient operationregardless of the adjusted position of the needle thereof.

A further object of the invention is to provide an air-bleed needlevalve of the class described which incorporates a filter to preventclogging of the air or fuel passages of the idling system in which thevalve is incorporated.

The foregoing and other objects and advantages of the invention will beapparent from the following detailed description thereof, suchconsideration being given also to the attached drawings, in which:

Figure 1 is an elevational section through a portion of a conventionalcarburetor manifold, having the novel needle valve incorporated in theidling fuel supply system thereof;

Figure 2 is an enlarged elevational section of the valve shown in Figure1;

Figure 3 is a section taken on the line 33 in Figure 2; and

Figure 4 is an enlarged elevational partial section of a slightlymodified form of the valve shown in Figure 1.

In the drawings, we have illustrated the needle valve of the presentinvention as incorporated in an up-draft carburetor of conventionaldesign although it will be realized that the device is equally useful inother types of carburetors. Only the upper manifold portion 5 of theconventional carburetor is shown, the manifold portion 5 being providedwith the usual attachment flanges 6 and bolt holes 1, whereby thecarburetor is secured to the intake manifold of an internal combustionengine.

The main supply of air-fuel mixture for high speed operation flowsthrough a main passageway 8, moving upwardly in the direction of thearrow shown in Figure 1, being regulated by a throttle valve 9 which isrotatable on a shaft in from a longitudinal or open throttle position toa transverse or closed throttle position in the usual manner.

When the throttle 9 is in nearly closed position, as illustrated inFigure 1 the rate of air flow through the main passageway 8 isrelatively small with the result that practically no fuel is suppliedthrough the main high speed jets of the carburetor in the venturi (notshown). Thus, for idling purposes, an auxiliary fuel supply must beprovided. In the present instance, this auxiliary fuel supply isprovided through a liquid fuel passage 12 formed integrally with themanifold 5, the passage 12 having its lower end located in a liquid fuelwell (not shown) whereby the partial vacuum condition existing above thethrottle during idling conditions will cause liquid fuel to rise in thepassageway i2 and discharge through a transverse connecting passagewayl3 into the main passageway 8. The rate at which liquid fuel isdelivered through the passageways l2 and I3 into the main passageway 8is regulated by means of a needle valve IS having a conical needleportion 3! which may be moved toward or away from a conical seat Hiformed in the transverse passageway l3.

The needle valve I6 is provided with a threaded shank 22 received in athreaded opening in the carburetor body 5. In order to hold the valve 15in any adjusted position thereof, a relatively stiff compression springIT is secured under the head thereof whereby to exert a constant axialthrust outwardly on the valve l6 whereby to prevent the same fromrotating due to the vibration of the engine.

For a detailed description of the construction of the valve 16,reference should now be had to Fig. 2, wherein it will be seen that thevalve is formed with a relatively large diameter threaded shank 22, areduced diameter needle portion at having a conical point 31. Agenerally flat head 23 is formed on the upper end of the shank 22, thehead being provided with peripheral serrations 26, and a transverse slot21. The upper and lower edges of the head 23 are heavily chamfered, asindicated by the reference characters 24 and 25.

In order to provide the filter hereinbefore mentioned, a cup-shaped capis pressed onto the head 23, having a light press fit with the points ofthe peripheral serrations 26.

An indentation 2! is formed in the upper wall of the cap 2!) whichindentation engages the top of the head 23 as illustrated in Figure 2,thus preventing the cap from coming into complete face-to-faceengagement with the upper surface of the head 23.

An air-bleed passageway is provided in the valve 16, comprising an axialpassage 28 connected by a plurality of transverse passages '19,

4 having their exits in the needle portion 38 at the lower end of thevalve I6. It will be noted that, in the form shown in Figure 4, thereare three transverse passages 29, although more may be provided ifdesired.

Thus, it will be noted that a passageway for air to be introduced withthe fuel through the transverse idling passageway 13, is formed in thevalve [6. The air enters this air-bleed passageway through theserrations 26 into a chamber 32 at the top of the valve. From thechamber 32, the air travels through the slot 21 into the axialpassageway 28 from whence it discharges through the radial passages 29adjacent the upper end of. the liquid fuel passageway 12. Practicallyall particles of dirt or other material are filtered out by the passageof the air through the numerous small spaces or channels formed by theserrations 26 and since there are a large number of these serrations,the tendency for the air passageway to become completely clogged isvirtually eliminated. It should be noted in passing that the relativelywide chamfers Z4 and 25 reduce the width of the serrated'periphery 26whereby to reduce the air friction pressure drop as the air passes intothe chamber 32.

It should also be noted that the velocity of the air passing through thevalve I6 is greatly reduced in the chamber 32 and that any smallparticles of heavy material which might have been drawn through theserrations 26 will tend to remain trapped in the chamber 32 due to thefact that they are no longer suspended by the moving air stream. Sincethe cap 20 is a light press fit on the head 23, it may be removed andcleaned occasionally in order to get rid of any particles of dirt whichmay adhere to the serrations 26 or may have become entrapped in thechamber 32.

It has been found by experimentation that the optimum position of thetransverse passageways 29 with respect to the vertical fuel passagewayit" is one in which the passageway 29 is neither directly opposed to theliquid fuel passageway (2 nor is 'on the opposite side of the valve 16from the pasageway 12, i. 6., pointing upwardly in Figure 1. Optimummixture of the air enter ing through the valve [6 with the liquid fuelmoving through the passageways l2 and iii is achieved when one, atleast, of the radial passageways 29 is somewhat transversely positionedwith respect to the vertical passageway if. It will be seen, therefore,that by providing a number of radial passages 29 angularly spaced aroundthe needle portion 30, one at least will always be located substantiallyat the side of the valve 16 and thus in optimum position.

Due to the fact that the needleportion 3!) is of considerably lessdiameter than the outside diameter of the threaded opening 15, anannular mixing chamber 33 is formed immediately above the upper end ofthe liquid fuel passageway 12. The air entering" into the mixing chamber33 through the orifices of the passageways 28 has ample opportunitytherefore to mix with or froth the liquid fuel, thus greatly increasingthe combustion eiiiciency thereof during the idling period.

In some carburetor designs, the seat against which the needle valve ismoved to close the idling fuel passageway is located a considerabledistance inwardly of the. liquid fuelpassageway [-2. In such instances,it is desirable that the needle valve I6 be modified to elongate theneedle portion as indicated by the reference character 30a in Figure 4.In such modified valves, the mouths of the transverse passageways 29 areplaced close to the juncture between the needle portion 3641 and thethreaded shank 22. It will be noted that, in the form illustrated inFigure 4, four transverse or radial passageways 29 have been employed,instead of three as shown in Figure 2.

While the valve shown and described herein is fully capable of achievingthe objects and providing the advantages hereinbefore stated, it iscapable of considerable modification without departing from the spiritof the invention. For this reason, we do not mean to be limited to theforms shown and described, but rather to the scope of the appendedclaims.

We claim:

1. For use with an air bleed needle valve of the type in which air isadmitted through a passageway formed in the shank of said valve, afilter for said air comprising: a head formed on the rearward end ofsaid valve, said head having a rearward opening of said passagewayformed therein; an imperforate cap received on said head to enclose allbut the undersurface thereof and to form an enclosed chamber adjacentsaid opening; and a plurality of relatively restricted channels formedin said head and opening in said undersurface to admit air into saidchamber.

2. For use with an air bleed needle valve of the type in which air isadmitted through a passageway formed in the shank of said valve, afilter for said air comprising: a head formed on the rearward end ofsaid valve, said head having the rearward opening of said passagewayformed therein and having a plurality of peripheral serrations formedtherein; and a cap received on said head to enclose all but theundersurface thereof and to form an enclosed chamber adjacent saidopening, said cap resting on the tips of said serrations whereby toadmit air through the spaces between said serrations into said chamber.

3. For use with an air bleed needle valve of the type in which air isadmitted through a passageway formed in the shank of said Valve, afilter for said air comprising: a head formed on the rearward end ofsaid valve, said head having the rearward opening of said passagewayformed in the top surface thereof; a cap received on said head toenclose all but the undersurface thereof, said cap having a transversewall with an indentation formed therein, said indentation beingpositioned and adapted to contact the top surface of said head and spaceC said transverse wall therefrom whereby to form an enclosed chamberadjacent said opening; and a plurality of relatively restricted channelsformed in said head and opening in said undersurface to admit air intosaid chamber.

4. For use with an air bleed needle valve of the type in which air isadmitted through a passageway formed in the shank of said valve, afilter for said air comprising: a head formed on the rearward end ofsaid valve, said head having a rearward opening of said passagewayformed in the top surface thereof and having a plurality of peripheralserrations formed therein; and a cap received on said head to encloseall but the undersurface thereof, said cap having a transverse wall withan indentation formed therein, said indentation being positioned andadapted to contact said top surface and space said transverse walltherefrom whereby to form an enclosed chamber adjacent said opening, theside a: wall of said cap resting on the tips of said serrations wherebyto admit air between said serrations from said undersurface into saidchamber.

5. An air filter for a needle valve member of 1 the type having an axialbore therein, said filter cemprising: a head formed on an end of saidvalve member with said bore opening in the top surface of said head andhaving longitudinally extending peripheral serrations formed in saidhead; and a cup-shaped, downturned cap having a press fit with saidhead, said cap being received on said head to surround all but theundersurface thereof, and having an indentation in the top wall thereofto space said wall from said top surface and to form a chamber adjacentsaid bore opening whereby air passing through said bore is filtered byalso passing longitudinaliy through said serrations.

CYRUS L. SNYDER.

JOHN W. SCHROEDER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,598,421 Brush Aug. 31, 19261,786,432 Kirk et al. Dec. 30, 1930 1,838,100 Liddell Dec. 29, 19312,043,895 Larrosa June 9, 1936 FOREIGN PATENTS Number Country Date114,185 Great Britain Mar. 19, 1918 257,168 Great Britain Aug. 26, 1926

